The Nearest Globular: Messier 4

[SkyViking (Rolf)]

Hi All,

Yes, another globular image from me
This one was taken a while ago on 1st May, but I didn't have time to process it until now. It also proved to be rather challenging because there was a bit of glare from a 55% illuminated Moon, combined with the large amounts of faint dust in the Antares region. The background is not completely flat but I believe the remaining irregularities are mostly due to the dust clouds.

Hi-res image available here (1.2MB): http://www.pbase.com/rolfolsen/image/123575176/original

Image details:
10" Serrurier truss Newtonian f/5
QSI 683wsg
LRGB 45:21:21:21

Messier 4 is the nearest globular cluster, being 2.2kpc or about 7,175 light years away. It is very prominent with the slightest optical aid, and is located just 1.3 degrees west of Antares in Scorpius. Messier 4 would be one of the most splendid globulars in the sky if it were not obscured by heavy clouds of dark interstellar matter. Interstellar absorption also reddens the color of the light from the cluster. However, it displays an angular diameter of more than that of the Full Moon, which corresponds to a actual diameter of 75 light years.
It is also one of the least concentrated globular clusters. The central core is much less dense than in many other globulars, such as 47 Tucanae.

BTW, I also created a Colour-Magnitude diagram for this globular and added it to my collection here: http://www.pbase.com/rolfolsen/colourmagnitude_diagrams

Hope you enjoy the view. Comments and critique is welcome as usual.

Regards,
Rolf

[jjjnettie (Jeanette)]

Ohhh, now that's a nice one. Well done , the star colour is lovely.

[John Hothersall]

Love the col mag diagrams showing blue straglers on all globs you hae imaged clearly. Rich colours show the orange blue contrast as M4 has a good magnitude range and stretches to a suprisingly large radius.

John.

[RobF (Rob)]

Nice write up Rolf. Wasn't aware it is the closest globs. A sentimental fav of mine from a dark windy morning 30 years ago through my 4.5" Newt

Pardon me being picky, but you seem to be getting ringing of stars, particularly the red ones. Are you deconvolving or applying unsharp masking a bit too aggressivly possibly? A softer look on the stars might look more appealing?

[Ross G]

Great photo Rolf.

I love the colours.


Ross.

[dj gravelrash (Dino)]

Wonderful--i was actually outside checking this out last night from the gold coast.

[Dennis]

Hi Rolf

This beautiful portrait of M4, like your others, is a just fabulous to look at and get lost in. You have the knack of making these common objects look somehow different, additionally spicing the whole package up with your engaging commentaries.

Cheers

Dennis

[SkyViking (Rolf)]

Originally Posted by jjjnettie

Ohhh, now that's a nice one. Well done , the star colour is lovely.

Thanks very much JJJ, this is also a very nice cluster visually. Always worth a look when you're in the area

Originally Posted by John Hothersall

Love the col mag diagrams showing blue straglers on all globs you hae imaged clearly. Rich colours show the orange blue contrast as M4 has a good magnitude range and stretches to a suprisingly large radius.
John.

Thanks John, yes M4 is very large indeed. I did some reading and the most obvious feature in the diagrams are actually the horizontal branch stars, the blue stragglers themselves are a bit fainter but show as an extension of the main sequence beyond the turnoff point, usually located directly below the horizontal branch.

Originally Posted by RobF

Nice write up Rolf. Wasn't aware it is the closest globs. A sentimental fav of mine from a dark windy morning 30 years ago through my 4.5" Newt
Pardon me being picky, but you seem to be getting ringing of stars, particularly the red ones. Are you deconvolving or applying unsharp masking a bit too aggressivly possibly? A softer look on the stars might look more appealing?

Thank you Rob, yeah this is a glorious sight also visually. I had a closer look but not sure where the ringing is? I didn't deconvolve but applied a very slight unsharp mask on the fainter stars only.

Originally Posted by Ross G

Great photo Rolf.
I love the colours.
Ross.

Thank you Ross, glad you liked it

Originally Posted by dj gravelrash

Wonderful--i was actually outside checking this out last night from the gold coast.

Thanks Dino, glad to hear that - I think M4 is often overlooked in favour of all the other splendours in the area.

Originally Posted by Dennis

Hi Rolf
This beautiful portrait of M4, like your others, is a just fabulous to look at and get lost in. You have the knack of making these common objects look somehow different, additionally spicing the whole package up with your engaging commentaries.
Cheers
Dennis

Thanks very much Dennis! I think these common sights also deserve some attention and they make for good bright targets when the Moon prevents deeper imaging
But I was lucky to get 19 hours of data just from the last 3 nights here so more images are in the pipeline